Partners in Practice

ISS2 2012

Partners in Practice is a quarterly newsletter designed specifically for the equine veterinarian and their staff. Merck Animal Health brings veterinarians the latest information in equine research and practice management in each issue.

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Testing
In February 2012 the American
Quarter Horse Association (AQHA)
began offering a genetic panel test
whereby a lab tests Quarter Horses
for HYPP, PSSM1, MH, GBED, and
HERDA for a ﬂat fee and records results on the horse's registration. There
are also several laboratories licensed
to offer individual genetic tests. The
Veterinary Genetics Laboratory at
the University of California, Davis
(UC Davis), performs HYPP and
GBED testing, and Monica Aleman,
MVZ, PhD, Dipl. ACVIM, at UC Davis
performs MH testing. The University
of Minnesota Veterinary Diagnostic
Laboratory provides PSSM1 and MH
testing. Vetgen, Animal Genetics, and
Progressive Molecular Diagnostics
Inc. perform GBED testing.
Researchers suspect several additional muscle disorders in horses,
Aquatic biting flies Larvae develop
in standing water (mosquitoes),
ﬂowing water (black ﬂies), wetland
mud (horse/deer ﬂies), or moist,
organically rich areas (biting
midges).
Filth flies Larvae develop in damp,
decaying organic debris (house ﬂy,
stable ﬂy) or in fresh cattle dung
pats (horn ﬂy, face ﬂy).
There are many ways to reduce
aquatic biting ﬂy breeding grounds
to eliminate larval production,
whereas chemical options for reducing these grounds are limited. For
instance, change stock tank water
weekly; remove or drain standing
water sources (such as wheelbarrows and buckets); and promote
good drainage on your property so
rain puddles do not persist. Control
weeds around buildings and bodies of water. Add ﬁsh that consume
mosquito larvae to stock tanks. You
might also place an insect growth
regulator (IGR) product to control
larvae in stock tanks. Treat water
sources not used by horses with
mosquito dunks containing bacteria
toxic to mosquitoes.
Effective ﬁlth ﬂy control begins
with source reduction through
managing manure properly. Remove
Researchers suspect
several additional muscle
disorders in horses, but have
not conﬁrmed them to have a
heritable basis.
— Dr. Stephanie Valberg
but they have not conﬁrmed them to
have a heritable basis. These include
recurrent exertional rhabdomyolysis (RER) in Thoroughbreds, type 2
PSSM in Quarter Horses and Warmbloods, and immune-mediated myositis in Quarter Horses. Researchers
recently identiﬁed chromosomal regions associated with RER, but they
have yet to identify a speciﬁc gene
and mutation. For now, veterinarians identify these muscle disorders
by interpreting the history, physical
exam ﬁndings, serum muscle enzyme
activity, and muscle biopsy ﬁndings.
manure from equine quarters daily,
and spread it thinly over an unoccupied pasture or arena to dry. You
can also treat manure with diatomaceous earth, which kills insects by
dehydrating them. In addition, releasing parasitic wasps can be a very
effective biological control method.
These tiny, stingless wasps parasitize and eventually kill ﬁlth ﬂy pupae
found in manure, soiled bedding,
old hay, etc. Veterinarians might
choose instead to use feed-through
ﬂy control. Manufacturers design
these supplements, which contain an
IGR, to pass through the horse in his
manure and prevent ﬂy larval development in the treated manure.
Controlling adult ﬂies is usually necessary as well, especially by
midsummer. Before you reach for
a pyrethroid insecticide-based ﬂy
repellent or premises spray, consider
these nonchemical options:
Install fans in horse barns; some
ﬂy species do not ﬂy well against
moving air.
The initial development of the
muscle biopsy technique for horses
and its subsequent use in equine
practice has helped researchers
uncover new muscle disorders and
facilitated the development of readily available genetic tests. Grants
from the AQHA, Morris Animal
Foundation, University of Minnesota
Equine Center, and Grayson Jockey
Club Research Foundation made
these discoveries possible.
Stephanie Valberg, DVM, PhD,
Dipl. ACVIM, ACVSMR, is a professor
of large animal medicine and director of the University of Minnesota's
Equine Center.
Adjust turnout schedules to keep
horses inside during times when
ﬂies are active.
Equip horses with protective
sheets and masks.
Install traps that target most adult
ﬂy species. Trap location is very
important; locate baited traps a
distance away from your clinic to
avoid attracting more ﬂies to your
property.
To summarize, customize your
ﬂy management program to the
speciﬁc ﬂy problems at your facility,
and utilize IPM strategies to minimize health risks to you and your
staff, clients, equine patients, and
the environment. For more information, go to www.extension.umn.
edu/distribution/livestocksystems/
DI8537.pdf.
Holly Ferguson, PhD, is an extension integrated pest management coordinator specialist with Washington
State University's Irrigated Agriculture
Research and Extension Center.